MADAGASCAR (III) 276 
its age, it is rather surprising that no rodent has adapted itself to 
such conditions. 
After my brief and unproductive stay here I left the Onilahy 
River with four bearers and went northwards in search of forest. 
Two of the bearers were carrying water, as the country to be 
traversed was absolutely dry. After a twenty-mile march through 
scrub and over rock we reached a village of about two hundred 
inhabitants. Their nearest water was the Onilahy River! 
The village was filthy, and as the only place available for me to 
sleep in was a dirty hovel about six feet square, I decided to go 
on in spite of being hot and tired. Just before nightfall we reached 
a small native settlement near the main Tulear-Ihosy road, about 
twenty-six miles from Tulear. This was quite a pleasant spot, and 
at least there was a nice hut to stay in. 
It was amazing to find people with their herds of cattle and 
goats, as well as pigs, fowls and dogs, living so far from water. 
There is enough rich soil in certain shallow depressions between 
the stony hills to support these people with such crops as cassava, 
maize, and sweet potatoes, which thrive in the rainy season. At 
such times water can be obtained when it is not actually running 
by digging in the water-courses, but as soon as the dry season com- 
mences it is unobtainable owing to the porous nature of the soil. 
From then on, for at least six months, the natives have to rely 
mainly on the roots of a wild yam (Dzoscorea) for their moisture. 
This plant has adapted itself to tide over long periods of drought 
by conserving an enormous amount of fluid in its roots in times 
of rain. The tubers are white, and average about eighteen inches 
long by six inches in diameter, and are as juicy as any water- 
melon. They are more or less tasteless, but are supposed to possess 
medicinal properties beneficial to the kidneys. I must say that 
during my stay of over a month in the district, during which 
time I had very little water but consumed large quantities of 
Dioscorea roots, I felt extremely fit, in spite of limited facilities 
for washing. 
In this locality the vegetation is a link between the sub-desert 
scrub and deciduous forest. The trees are from ten to twenty feet 
high with a dense, almost impenetrable undergrowth of scrub. 
